As handsets and other wireless communication devices become smaller and embedded with more applications, new antenna designs are required to address inherent limitations of these devices. Many such devices require coverage in low-frequency ranges, sometimes in addition to higher frequency communication ranges.
Wireless devices are also experiencing a convergence with other mobile electronic devices. Due to increases in data transfer rates and processor and memory resources, it has become possible to offer a myriad of products and services on wireless devices that have typically been reserved for more traditional electronic devices. Antennas in these devices will need to operate over multiple frequencies, including traditional cellular communication frequencies of, for example, 800/900 Mhz and 1800/1900 Mhz.
Because of consumer demands and other trends in the wireless device industry, product requirements are becoming increasingly smaller, thus components for these devices will need to be smaller and novel solutions for fitting antennas and other components within the device will be needed to be provide competitive low profile devices.
As antennas are made smaller, problems such as coupling of antenna elements and other interferences are increasingly observed. To provide modern practical antennas and wireless devices, a need for novel solutions for antenna optimization is needed.
This invention includes improvements to known antenna elements such as Isolated Magnetic Dipole (IMD) antennas. Isolated Magnetic Dipole antennas are disclosed in commonly owned U.S. Pat. No. 6,456,243; U.S. Pat. No. 6,567,053; U.S. Pat. No. 6,677,915; and U.S. Pat. No. 6,717,551; the entire contents of which are hereby incorporated by reference.
This invention further includes improvements to antenna circuit designs, for example designs which incorporate an antenna into the PCB board of the antenna circuit. FR-4, an abbreviation for Flame Retardant 4, is a type of material used for making a printed circuit board (PCB). It describes the board substrate, with no copper layer. The FR-4 used in PCBs is typically UV stabilized with a tetra functional epoxy resin system. FR-4 is similar to an older material called G-10. G-10 lacked FR-4's self-extinguishing flammability-characteristics. FR-4 has widely replaced G-10 in most applications. Furthermore, this invention utilizes known methods for chemical etching or printing of conductors on a surface of a PCB board.
Those having skill in the art will recognize that antennas used within portable electronic devices have a variety of performance related problems. Particularly, when placed on a printed circuit board, these antennas tend to couple to the electrical components of the circuit. Additionally, the circuit board acts as a ground plane for which the antenna operates with. Therefore, performance of these antennas is largely affected by dimensional size and proximity of adjacent circuit boards.
Limitations with respect to the size of a printed circuit board are generally a product of the circuit components. In practice, printed circuit boards for portable electronic devices are generally not designed for antenna optimization, but rather they are designed to fit each of the required components within a minimal volume. For this reason, there is a need for an antenna capable of operating over multiple bands while preserving a minimal volume requirement and having an optimized performance in light of minimal circuit board dimensions.